Hot melt adhesive applicator



I United States Patent [1113,548,781

[72] Inventor Helmut O- Hornung 2,835,221 5/1958 Slayter et al. 118/202A1toona,Pa. 3,030,915 4/1962 Shannon 118/202 211 App]. No. 739,0793,124,476 3/1964 Park et a1..... 118/63X [22] Filed June 21,19683,412,707 11/1968 West 118/5 [45] Patented Dec. 22,1970 [73] Assignee F.1.. Smlthe Machine Company, Inc. Zgggigfi'gg 32115 McIntoshDuncansvl11e,Pa. a corporation of New York [54] WE APPLICATOR ABSTRACT:A hot melt adhesive applicator for application to a paper line, such asspaced or overlapped envelopes, 1n WhlCh [52] US. Cl. 11815, the t f toi resiliently covered and is located in a 118/2 chamber having acontrolled temperature environment. The [51] Int B059 1/00, applicatoris provided with a contiguous melt box and B059 11/00 chamber. The meltbox is provided with an opening in a wall of Search u I 18/5, thereofthrough which a part of the dispensing roller projects 212, 216,Digest)? 117/1193 thereby essentially filling the opening. Thedispensing roller picks up the adhesive and passes it to the transferroller. The [56] References Cited chamber is provided with a hot airenvironment in order to UNITED STATES PATENTS control the temperature ofthe transfer roller, the latter having 2,693,429 1 H1954 Radtke et a] 118/202X a resilient covering.

IfATENTED(15!:221970 3548.781

INVENTOR Nsvs IHELMUT 0. HORNUIVG HOT MELT ADHESIVE APPLICATORBACKGROUND OF THE INVENTION A hot melt applicator is known as a heatedapplicator roller or a direct applicator roller which is in the form ofa smooth, hard-surfaced cylinder that is etched to a particular depthand design. Thus, when the cylinder is rotated in the hot melt adhesive,it is coated uniformly. Thereafter, a scraper or doctor blade scrapesoff the surface of the cylinder leaving only that adhesive materialwhich is in the etched area. The rotating cylinder then is adapted toapply the adhesive to the paper material. The use of resilient materialeliminates high precision machining operations necessary formanufacturing metallic rolls.

In addition, the use of resilient material provides a more evendistribution of adhesives to the paper line.

SUMMARY OF THE INVENTION It is an object of the invention to provide astandard hardsurfaced cylinder rotating against another cylinderprovided with a resilient covering. The hard-surfaced cylinder isadapted for rotation in molten adhesive in place of the expensivegravure cylinder.

The molten adhesive is transferred evenly by the resilient material onthe other cylinder to the paper line. However, the transfer roll withthe resilient covering is not heated internally as is the case with thestandard hard-surfaced gravure cylinder since the high temperaturesrequired in heating the transfer roll would destroy the resilientcovering.

In order to overcome the heating problem with respect to the transferroll, a controlled temperature environment has been evolved to keep theresilient applicator at the proper temperature without damaging theresilient coating thereof.

Another object of the present invention is to provide a resilientcovered transfer roll which can be applied to either individual oroverlapped blanks on a web form.'

BRIEF DESCRIPTION OF THE DRAWING Further objects and advantages of thisinvention will become apparent from the following description which willbe best understood by reference to the appended drawing in which:

FIG. 1 is a diagrammatic sectional view of the hot melt adhesiveapplicator constructed in accordance with the teachings of the presentinvention; and

FIG. 2 is an alternative embodiment of the hot melt adhesive applicatoras disclosed in FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, the hot meltapplicator constructed in accordance with the present inventioncomprises a melt box in which a quantity of adhesive 12 is locatedtherein. The temperature in the melt box 10 is thermostaticallycontrolled by thermostat 14. Mounted partially within the melt box 10 isa rotatable hard surface roller 16. The part of the roller 16 that isnot located within the melt box 10 projects through opening 18. Theroller 16 when rotating picks up an excess of molten adhesive which isscraped off by an adjustable scraper 20 adjacent to the opening 18 inthe melt box 10. Unused adhesive 12 is transferredback to the melt box10 through the clearance 22 formed between the box 10 and the roller 16.

In order to overcome the problem of heat transfer to the transfer roll24 having resilient coverings 26 on selected areas thereof, a controlledtemperature environment has been achieved. In this regard, the surfacetemperature of the applicator wheel 24 is maintained at a slightlyhigher temperature than the temperature of the melt box 10. The heatedenvironment in the chamber 28 is controlled in a thermostatihousin l5and the roller 24.

The eed rollers 38 and 40 engage the paper line 42 and propel the webeither in the form of individual spaced blanks or overlapped blanks B inthe direction of the arrow C. The blanks are engaged by the resilientsurfaces 26 of the transfer roll 24 in the proper timed relationship inorder to place the adhesive at the proper location on each of the blanksB.

FIG. 2 shows a hot melt adhesive applicator such as shown in FIG. 1,however, the transfer roll 42 therein is provided with an uninterruptedresilient covering 44 instead of the discontinuous resilient covering 26shown in FIG. 1. The structure of FIG. 2 is especially adapted for theapplication of adhesive to individual sheets in an overlap condition.

I claim:

1. A hot melt adhesive applicator for a line of paper comprising a meltbox provided with an opening in a wall thereof, said melt box having anadhesive therein, a dispensing roller at least partly in said melt boxin contact with said adhesive, means for controlling and maintaining theprescribed temperature in said melt box, a chamber operatively connectedto said melt box, part of said dispensing roller projecting through theopening in said melt box into said chamber and to essentially fill saidopening, a transfer roller in said chamber having a coating of resilientmaterial, said transfer roller taking adhesive from said dispensingroller on said resilient material and transferring the same to said lineof paper, and a constantly controlled hot air environment in saidchamber to control the temperature of the transfer roller therein.

2. A hot melt adhesive applicator as claimed in claim I I wherein saidtransfer roll has discontinuous resilient surfaces.

3. A hot melt adhesive applicator as claimed in claim 1 wherein saidtransfer roll has a continuous, outer, resilient surface.

4. A hot melt adhesive applicator fora line of paper comprising a meltbox provided with an opening in a wall thereof, said melt box having anadhesive therein, a dispensing roller at least partly in said melt boxin contact with said adhesive, a chamber adjacent and operativelyconnected to said melt box, means in said chamber for maintaining asurface temperature therein which is higher than the surface,temperature in said melt'box, part of said dispensing roller projectingthrough the opening in said melt box into said chamber and essentiallyfilling said opening, and a transfer roller in said chamber hav ing acoating of resilient material, said transfer roller taking adhesive fromsaid dispensing roller on said resilient material and transferring thesame to said line of paper.

5. A hot melt adhesive applicator fora line of paper comprising a meltbox provided with an opening therein, said melt box having an adhesivetherein, a dispensing roller at least partly in said melt box and incontact with said adhesive, means for controlling and maintaining theprescribed temperature in said melt box, a chamber operatively connectedto said melt box, part of said dispensing roller projecting through theopening in said melt box into said chamber, a transfer roller in saidchamber having a coating of resilient material, said transfer rollertaking adhesive from said dispensing roller on said resilient materialand transferring the same to said line of paper, and means in saidchamber for controlling the temperature therein being a blower having aplurality of blades and a resistance element.

6. A hot melt adhesive applicator as claimed in claim 5 wherein saidchamber is contiguous to said melt box, and said chamber is providedwith an outlet adjacent to said transfer roller whereby hot airpropelled by said blower is ejected through said outlet.

